Hyperfine Interactions in CeT₂Ge₂ (T = Mn, Co) Heavy Fermions Compounds Measured by TDPAC

Abstract

Time Differential Perturbed γ–γ Angular Correlation (TDPAC) technique was used to measure the magnetic hyperfine field at both Ge and Ce sites in CeMn₂Ge₂ and CeCo₂Ge₂ intermetallic compounds. The ¹¹¹In (¹¹¹Cd) probe nuclei was used to investigate the hyperfine interaction at Ge sites, while the ¹⁴⁰La (¹⁴⁰Ce) nuclei was used to measure the magnetic hyperfine field at Ce site. The present measurements cover the temperature ranges from 10–460 K for CeMn₂Ge₂ and 9–295 K for CeCo₂Ge₂, respectively. The result for ¹¹¹Cd probe showed two distinct electric quadrupole frequencies above magnetic transition temperatures, in both compounds and a combined interaction in the magnetic region. The temperature dependence of the magnetic hyperfine field at ¹¹¹Cd at Mn site for the CeMn₂Ge₂ compound showed a transition from ferromagnetic to antiferromagnetic phase around 320 K and from antiferromagnetic to paramagnetic phase at 420 K. While a small magnetic field was measured on ¹¹¹Cd at Co site, no magnetic field on ¹⁴⁰Ce site was observed in CeCo₂Ge₂.